Systems and methods for acquiring calibration data usable in a pause oximeter

ABSTRACT

The present disclosure includes a pulse oximeter attachment having an accessible memory. In one embodiment, the pulse oximeter attachment stores calibration data, such as, for example, calibration data associated with a type of a sensor, a calibration curve, or the like. The calibration data is used to calculate physiological parameters of pulsing blood.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/153,263, filed May 21, 2002, entitled “System And Method ForAltering A Display Mode Based On A Gravity-Responsive Sensor,” which isa continuation of U.S. patent application Ser. No. 09/516,110, filedMar. 1, 2000, entitled “Universal/Upgrading Pulse Oximeter,” nowallowed, which is a continuation of U.S. patent application Ser. No.09/491,175, filed Jan. 25, 2000, entitled “Universal/Upgrading PulseOximeter,” now abandoned, and application Ser. No 09/491,175 claims thebenefit of U.S. Provisional Application No. 60/161,565, filed Oct. 26,1999, entitled “Improved Universal/Upgrading Pulse Oximeter, andapplication Ser. No. 60/117,097, filed Jan. 25, 1999, entitled“Universal/Upgrading Pulse Oximeter.” Each of the foregoing applicationsis incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002] Oximetry is the measurement of the oxygen level status of blood.Early detection of low blood oxygen level is critical in the medicalfield, for example in critical care and surgical applications, becausean insufficient supply of oxygen can result in brain damage and death ina matter of minutes. Pulse oximetry is a widely accepted noninvasiveprocedure for measuring the oxygen saturation level of arterial blood,an indicator of oxygen supply. A pulse oximetry system consists of asensor applied to a patient, a pulse oximeter, and a patient cableconnecting the sensor and the pulse oximeter.

[0003] The pulse oximeter may be a standalone device or may beincorporated as a module or built-in portion of a multiparameter patientmonitoring system, which also provides measurements such as bloodpressure, respiratory rate and EKG. A pulse oximeter typically providesa numerical readout of the patient's oxygen saturation, a numericalreadout of pulse rate, and an audible indicator or “beep” that occurs inresponse to each pulse. In addition, the pulse oximeter may display thepatient's plethysmograph, which provides a visual display of thepatient's pulse contour and pulse rate.

SUMMARY OF THE INVENTION

[0004]FIG. 1 illustrates a prior art pulse oximeter 100 and associatedsensor 110. Conventionally, a pulse oximetry sensor 110 has LED emitters112, typically one at a red wavelength and one at an infraredwavelength, and a photodiode detector 114. The sensor 110 is typicallyattached to an adult patient's finger or an infant patient's foot. For afinger, the sensor 110 is configured so that the emitters 112 projectlight through the fingernail and through the blood vessels andcapillaries underneath. The LED emitters 112 are activated by drivesignals 122 from the pulse oximeter 100. The detector 114 is positionedat the fingertip opposite the fingernail so as to detect the LED emittedlight as it emerges from the finger tissues. The photodiode generatedsignal 124 is relayed by a cable to the pulse oximeter 100.

[0005] The pulse oximeter 100 determines oxygen saturation (SpO₂) bycomputing the differential absorption by arterial blood of the twowavelengths emitted by the sensor 110. The pulse oximeter 100 contains asensor interface 120, an SpO₂ processor 130, an instrument manager 140,a display 150, an audible indicator (tone generator) 160 and a keypad170. The sensor interface 120 provides LED drive current 122 thatalternately activates the sensor red and IR LED emitters 112. The sensorinterface 120 also has input circuitry for amplification and filteringof the signal 124 generated by the photodiode detector 114, whichcorresponds to the red and infrared light energy attenuated fromtransmission through the patient tissue site. The SpO₂ processor 130calculates a ratio of detected red and infrared intensities, and anarterial oxygen saturation value is empirically determined based on thatratio. The instrument manager 140 provides hardware and softwareinterfaces for managing the display 150, audible indicator 160 andkeypad 170. The display 150 shows the computed oxygen status, asdescribed above. The audible indicator 160 provides the pulse beep aswell as alarms indicating desaturation events. The keypad 170 provides auser interface for such things as alarm thresholds, alarm enablement,and display options.

[0006] Computation of SpO₂ relies on the differential light absorptionof oxygenated hemoglobin, HbO₂, and deoxygenated hemoglobin, Hb, todetermine their respective concentrations in the arterial blood.Specifically, pulse oximetry measurements are made at red and IRwavelengths chosen such that deoxygenated hemoglobin absorbs more redlight than oxygenated hemoglobin, and, conversely, oxygenated hemoglobinabsorbs more infrared light than deoxygenated hemoglobin, for example660 nm (red) and 905 nm (IR).

[0007] To distinguish between tissue absorption at the two wavelengths,the red and IR emitters 112 are provided drive current 122 so that onlyone is emitting light at a given time. For example, the emitters 112 maybe cycled on and off alternately, in sequence, with each only active fora quarter cycle and with a quarter cycle separating the active times.This allows for separation of red and infrared signals and removal ofambient light levels by downstream signal processing. Because only asingle detector 114 is used, it responds to both the red and infraredemitted light and generates a time-division-multiplexed (“modulated”)output signal 124. This modulated signal 124 is coupled to the input ofthe sensor interface 120.

[0008] In addition to the differential absorption of hemoglobinderivatives, pulse oximetry relies on the pulsatile nature of arterialblood to differentiate hemoglobin absorption from absorption of otherconstituents in the surrounding tissues. Light absorption betweensystole and diastole varies due to the blood volume change from theinflow and outflow of arterial blood at a peripheral tissue site. Thistissue site might also comprise skin, muscle, bone, venous blood, fat,pigment, etc., each of which absorbs light. It is assumed that thebackground absorption due to these surrounding tissues is invariant andcan be ignored. Thus, blood oxygen saturation measurements are basedupon a ratio of the time-varying or AC portion of the detected red andinfrared signals with respect to the time-invariant or DC portion:

[0009] RD/IR=(Red_(AC)/Red_(DC)/(IR) _(AC)/IR_(DC)).

[0010] The desired SpO₂ measurement is then computed from this ratio.The relationship between RD/IR and SPO₂ is most accurately determined bystatistical regression of experimental measurements obtained from humanvolunteers and calibrated measurements of oxygen saturation. In a pulseoximeter device, this empirical relationship can be stored as a“calibration curve” in a read-only memory (ROM) look-up table so thatSpO₂ can be directly read-out of the memory in response to input RD/IRmeasurements.

[0011] Pulse oximetry is the standard-of-care in various hospital andemergency treatment environments. Demand has lead to pulse oximeters andsensors produced by a variety of manufacturers. Unfortunately, there isno standard for either performance by, or compatibility between, pulseoximeters or sensors. As a result, sensors made by one manufacturer areunlikely to work with pulse oximeters made by another manufacturer.Further, while conventional pulse oximeters and sensors are incapable oftaking measurements on patients with poor peripheral circulation and arepartially or fully disabled by motion artifact, advanced pulse oximetersand sensors manufactured by the assignee of the present invention arefunctional under these conditions. This presents a dilemma to hospitalsand other caregivers wishing to upgrade their patient oxygenationmonitoring capabilities. They are faced with either replacing all oftheir conventional pulse oximeters, including multiparameter patientmonitoring systems, or working with potentially incompatible sensors andinferior pulse oximeters manufactured by various vendors for the pulseoximetry equipment in use oat the installation.

[0012] Hospitals and other caregivers are also plagued by the difficultyof monitoring patients as they are transported from one setting toanother. For example, a patient transported by ambulance to a hospitalemergency room will likely be unmonitored during the transition fromambulance to the ER and require the removal and replacement ofincompatible sensors in the ER. A similar problem is faced within ahospital as a patient is moved between surgery, ICU and recoverysettings. Incompatibility and transport problems are exacerbated by theprevalence of expensive and non-portable multi-parameter patientmonitoring systems having pulse oximetry modules as one measurementparameter.

[0013] The Universal/Upgrading Pulse Oximeter (UPO) according to thepresent invention is focused on solving these performance,incompatibility and transport problems. The UPO provides a transportablepulse oximeter that can stay with and continuously monitor the patientas they are transported from setting to setting. Further, the UPOprovides a synthesized output that drives the sensor input of otherpulse oximeters. This allows the UPO to function as a universalinterface that matches incompatible sensors with other pulse oximeterinstruments. Further, the UPO acts as an upgrade to existing pulseoximeters that are adversely affected by low tissue perfusion and motionartifact. Likewise, the UPO can drive a SpO₂ sensor input ofmultiparameter patient monitoring systems, allowing the UPO to integrateinto the associated multiparameter displays, patient record keepingsystems and alarm management functions.

[0014] One aspect of the present invention is a measurement apparatuscomprising a sensor, a first pulse oximeter and a waveform generator.The sensor has at least one emitter and an associated detectorconfigured to attach to a tissue site. The detector provides anintensity signal responsive to the oxygen content of arterial blood atthe tissue site. The first pulse oximeter is in communication with thedetector and computes an oxygen saturation measurement based on theintensity signal. The waveform generator is in communication with thefirst pulse oximeter and provides a waveform based on the oxygensaturation measurement. A second pulse oximeter is in communication withthe waveform generator and displays an oxygen saturation value based onthe waveform. The waveform is synthesized so that the oxygen saturationvalue is generally equivalent to the oxygen saturation measurement.

[0015] In another aspect of the present invention, a measurementapparatus comprises a first sensor port connectable to a sensor, anupgrade port, a signal processor and a waveform generator. The upgradeport is connectable to a second sensor port of a physiologicalmonitoring apparatus. The signal processor is configured to compute aphysiological measurement based on a signal input to the first sensorport. The waveform generator produces a waveform based on thephysiological measurement, and the waveform is available at the upgradeport. The waveform is adjustable so that the physiological monitoringapparatus displays a value generally equivalent to the physiologicalmeasurement when the upgrade port is attached to the second sensor port.

[0016] Yet another aspect of the present invention is a measurementmethod comprising the steps of sensing an intensity signal responsive tothe oxygen content of arterial blood at a tissue site and computing anoxygen saturation measurement based on the intensity signal. Other stepsare generating a waveform based on the oxygen saturation measurement andproviding the waveform to the sensor inputs of a pulse oximeter so thatthe pulse oximeter displays an oxygen saturation value generallyequivalent to the oxygen saturation measurement.

[0017] An additional aspect of the present invention is a measurementmethod comprising the steps of sensing a physiological signal, computinga physiological measurement based upon the signal, and synthesizing awaveform as a function of the physiological measurement. A further stepis outputting the waveform to a sensor input of a physiologicalmonitoring apparatus. The synthesizing step is performed so that themeasurement apparatus displays a value corresponding to thephysiological measurement.

[0018] A further aspect of the present invention is a measurementapparatus comprising a first pulse oximeter for making an oxygensaturation measurement and a pulse rate measurement based upon anintensity signal derived from a tissue site. Also included is a waveformgeneration means for creating a signal based upon the oxygen saturationmeasurement and the pulse rate measurement. In addition, there is acommunication means for transmitting the signal to a second pulseoximeter.

[0019] Another aspect of the present invention is a measurementapparatus comprising a portable portion having a sensor port, aprocessor, a display, and a docking connector. The sensor port isconfigured to receive an intensity signal responsive to the oxygencontent of arterial blood at a tissue site. The processor is programmedto compute an oxygen saturation value based upon the intensity signaland to output the value to the display. A docking station has a portableconnector and is configured to accommodate the portable so that thedocking connector mates with the portable connector. This provideselectrical connectivity between the docking station and the portable.The portable has an undocked position separate from the docking stationin which the portable functions as a handheld pulse oximeter. Theportable also has a docked position at least partially retained withinthe docking station in which the combination of the portable and thedocking station has at least one additional function compared with theportable in the undocked position.

[0020] A further aspect of the present invention is a measurementapparatus configured to function in both a first spatial orientation anda second spatial orientation. The apparatus comprises a sensor portconfigured to receive a signal responsive to a physiological state. Theapparatus also has a tilt sensor providing an output responsive togravity. In addition, there is a processor in communication with thesensor port and the tilt sensor output. The processor is programmed tocompute a physiological measurement value based upon the signal and todetermine whether the measurement apparatus is in the first orientationor the second orientation based upon the tilt sensor output. A displayhas a first mode and a second mode and is driven by the processor. Thedisplay shows the measurement value in the first mode when the apparatusis in the first orientation and shows the measurement value in thesecond mode when the apparatus is in the second orientation.

[0021] Another aspect of the present invention is a measurement methodcomprising the steps of sensing a signal responsive to a physiologicalstate and computing physiological measurement based on the signal.Additional steps are determining the spatial orientation of a tiltsensor and displaying the physiological measurement in a mode that isbased upon the determining step.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a block diagram of a prior art pulse oximeter;

[0023]FIG. 2 is a diagram illustrating a patient monitoring systemincorporating a universal/upgrading pulse oximeter (UPO) according tothe present invention;

[0024]FIG. 3 is top level block diagram of a UPO embodiment;

[0025]FIG. 4 is a detailed block diagram of the waveform generatorportion of the UPO embodiment shown in FIG. 3;

[0026]FIG. 5 is an illustration of a handheld embodiment of the UPO;

[0027]FIG. 6 is a top level block diagram of another UPO embodimentincorporating a portable pulse oximeter and a docking station;

[0028]FIG. 7 is a detailed block diagram of the portable pulse oximeterportion of FIG. 6;

[0029]FIG. 8A is an illustration of the portable pulse oximeter userinterface, including a keyboard and display;

[0030] FIGS. 8B-C are illustrations of the portable pulse oximeterdisplay showing portrait and landscape modes, respectively;

[0031]FIG. 9 is a detailed block diagram of the docking station portionof FIG. 6;

[0032]FIG. 10 is a schematic of the interface cable portion of FIG. 6;

[0033]FIG. 11A is a front view of an embodiment of a portable pulseoximeter;

[0034]FIG. 11B is a back view of a portable pulse oximeter;

[0035]FIG. 12A is a front view of an embodiment of a docking station;

[0036]FIG. 12B is a back view of a docking station;

[0037]FIG. 13 is a front view of a portable docked to a docking station;and

[0038]FIG. 14 is a block diagram of one embodiment of a local areanetwork interface for a docking station.

DETAILED DESCRIPTION

[0039]FIG. 2 depicts the use of a Universal/Upgrading Pulse Oximeter(“UPO”) 210 to perform patient monitoring. A pulse oximetry sensor 110is attached to a patient (not illustrated) and provides the UPO 210 witha modulated red and IR photo-plethysmograph signal through a patientcable 220. The UPO 210 computes the patient's oxygen saturation andpulse rate from the sensor signal and, optionally, displays thepatient's oxygen status. The UPO 210 may incorporate an internal powersource 212, such as common alkaline batteries or a rechargeable powersource. The UPO 210 may also utilize an external power source 214, suchas standard 110V AC coupled with an external step-down transformer andan internal or external AC-to-DC converter.

[0040] In addition to providing pulse oximetry measurements, the UPO 210also separately generates a signal, which is received by a pulseoximeter 268 external to the UPO 210. This signal is synthesized fromthe saturation calculated by the UPO 210 such that the external pulseoximeter 268 calculates the equivalent saturation and pulse rate ascomputed by the UPO 210. The external pulse oximeter 268 receiving theUPO signal may be a patient monitoring system (MPMS) 260 incorporating apulse oximeter module 268, a standalone pulse oximeter instrument, orany other host instrument capable of measuring SpO₂. The MPMS 260depicted in FIG. 2 has a rack 262 containing a number of modules formonitoring such patient parameters as blood pressure, EKG, respiratorygas, and SpO₂. The measurements made by these various modules are shownon a multiparameter display 264, which is typically a video (CRT)device. The UPO 210 is connected to an existing MPMS 260 with a cable230, advantageously integrating the UPO oxygen status measurements withother MPMS measurements. This allows the UPO calculations to be shown ona unified display of important patient parameters, networked with otherpatient data, archived within electronic patient records andincorporated into alarm management, which are all MPMS functionsconvenient to the caregiver.

[0041]FIG. 3 depicts the major functions of the UPO 210, including aninternal pulse oximeter 310, a waveform generator 320, a power supply330 and an optional display 340. Attached to the UPO 210 are a sensor110 and an external pulse oximeter 260. The internal pulse oximeter 310provides the sensor 110 with a drive signal 312 that alternatelyactivates the sensor's red and IR LEDs, as is well-known in the art. Acorresponding detector signal 314 is received by the internal pulseoximeter 310. The internal pulse oximeter 310 computes oxygensaturation, pulse rate, and, in some embodiments, other physiologicalparameters such as pulse occurrence, plethysmograph features andmeasurement confidence. These parameters 318 are output to the waveformgenerator 320. A portion of these parameters may also be used togenerate display drive signals 316 so that patient status may be readfrom, for example, an LED or LCD display module 340 on the UPO.

[0042] The internal pulse oximeter 310 may be a conventional pulseoximeter or, for upgrading an external pulse oximeter 260, it may be anadvanced pulse oximeter capable of low perfusion and motion artifactperformance not found in conventional pulse oximeters. An advanced pulseoximeter for use as an internal pulse oximeter 310 is described in U.S.Pat. No. 5,632,272 assigned to the assignee of the present invention andincorporated herein by reference. An advanced pulse oximetry sensor foruse as the sensor 110 attached to the internal pulse oximeter 310 isdescribed in U.S. Pat. No. 5,638,818 assigned to the assignee of thepresent invention and incorporated herein by reference. Further, a lineof advanced Masimo SET® pulse oximeter OEM boards and sensors areavailable from the assignee of the present invention.

[0043] The waveform generator 320 synthesizes a waveform, such as atriangular waveform having a sawtooth or symmetric triangle shape, thatis output as a modulated signal 324 in response to an input drive signal322. The drive input 322 and modulation output 324 of the waveformgenerator 320 are connected to the sensor port 262 of the external pulseoximeter 260. The synthesized waveform is generated in a manner suchthat the external pulse oximeter 260 computes and displays a saturationand a pulse rate value that is equivalent to that measured by theinternal pulse oximeter 310 and sensor 110. In the present embodiment,the waveforms for pulse oximetry are chosen to indicate to the externalpulse oximeter 260 a perfusion level of 5%. The external pulse oximeter260, therefore, always receives a strong signal. In an alternativeembodiment, the perfusion level of the waveforms synthesized for theexternal pulse oximeter can be set to indicate a perfusion level at orclose to the perfusion level of the patient being monitored by theinternal pulse oximeter 310. As an alternative to the generatedwaveform, a digital data output 326, is connected to the data port 264of the external pulse oximeter 260. In this manner, saturation and pulserate measurements and also samples of the unmodulated, synthesizedwaveform can be communicated directly to the external pulse oximeter 260for display, bypassing the external pulse oximeter's signal processingfunctions. The measured plethysmograph waveform samples output from theinternal pulse oximeter 310 also may be communicated through the digitaldata output 326 to the external pulse oximeter 260.

[0044] It will be understood from the above discussion that thesynthesized waveform is not physiological data from the patient beingmonitored by the internal pulse oximeter 310, but is a waveformsynthesized from predetermined stored waveform data to cause theexternal pulse oximeter 260 to calculate oxygen saturation and pulserate equivalent to or generally equivalent (within clinicalsignificance) to that calculated by the internal pulse oximeter 310. Theactual physiological waveform from the patient received by the detectoris not provided to the external pulse oximeter 260 in the presentembodiment. Indeed, the waveform provided to the external pulse oximeterwill usually not resemble the plethysmographic waveform of physiologicaldata from the patient being monitored by the internal pulse oximeter260.

[0045] The cable 230 (FIG. 2) attached between the waveform generator320 and external pulse oximeter 260 provides a monitor ID 328 to theUPO, allowing identification of predetermined external pulse oximetercalibration curves. For example, this cable may incorporate an encodingdevice, such as a resistor, or a memory device, such as a PROM 1010(FIG. 10) that is read by the waveform generator 320. The encodingdevice provides a value that uniquely identifies a particular type ofexternal pulse oximeter 260 having known calibration curve, LED driveand modulation signal characteristics. Although the calibration curvesof the external pulse oximeter 260 are taken into account, thewavelengths of the actual sensor 110, advantageously, are not requiredto correspond to the particular calibration curve indicated by themonitor ID 328 or otherwise assumed for the external pulse oximeter 260.That is, the wavelength of the sensor 110 attached to the internal pulseoximeter 310 is not relevant or known to the external pulse oximeter260.

[0046]FIG. 4 illustrates one embodiment of the waveform generatorportion 320 of the UPO 210 (FIG. 3). Although this embodiment isillustrated and described as hardware, one of ordinary skill willrecognize that the functions of the waveform generator may beimplemented in software or firmware or a combination of hardware,software and firmware. The waveform generator 320 performs waveformsynthesis with a waveform look-up table (“LUT”) 410, a waveform shaper420 and a waveform splitter 430. The waveform LUT 410 is advantageouslya memory device, such as a ROM (read only memory) that contains samplesof one or more waveform portions or segments containing a singlewaveform. These stored waveform segments may be as simple as a singleperiod of a triangular waveform, having a sawtooth or symmetric triangleshape, or more complicated, such as a simulated plethysmographic pulsehaving various physiological features, for example rise time, fall timeand dicrotic notch.

[0047] The waveform shaper 420 creates a continuous pulsed waveform fromthe waveform segments provided by the waveform LUT 410. The waveformshaper 420 has a shape parameter input 422 and an event indicator input424 that are buffered 470 from the parameters 318 output from theinternal pulse oximeter 310 (FIG. 3). The shape parameter input 422determines a particular waveform segment in the waveform LUT 410. Thechosen waveform segment is specified by the first address transmitted tothe waveform LUT 410 on the address lines 426. The selected waveformsegment is sent to the waveform shaper 420 as a series of samples on thewaveform data lines 412.

[0048] The event indicator input 424 specifies the occurrence of pulsesin the plethysmograph waveform processed by the internal pulse oximeter310 (FIG. 3). For example, the event indicator may be a delta time fromthe occurrence of a previously detected falling pulse edge or thisindicator could be a real time or near real time indicator of the pulseoccurrence. The waveform shaper 420 accesses the waveform LUT 410 in amanner to create a corresponding delta time between pulses in thesynthesized waveform output 428. In one embodiment, the waveform shaperis clocked at a predetermined sample rate. From a known number ofsamples per stored waveform segment and the input delta time from theevent indicator, the waveform shaper 420 determines the number ofsequential addresses to skip between samples and accesses the waveformLUT 410 accordingly. This effectively “stretches” or “shrinks” theretrieved waveform segment so as to fit in the time between twoconsecutive pulses detected by the UPO.

[0049] The waveform splitter 430 creates a first waveform 432corresponding to a first waveform (such a red wavelength) expected bythe external pulse oximeter 260 (FIG. 3) and a second waveform (such asinfrared) 434 expected by the external pulse oximeter 260. The relativeamplitudes of the first waveform 432 and second waveform 434 areadjusted to correspond to the ratio output 444 from a calibration curveLUT 440. Thus, for every value of measured oxygen saturation at the satinput 442, the calibration curve LUT 440 provides a corresponding ratiooutput 444 that results in the first waveform 432 and the secondwaveform 434 having an amplitude ratio that will be computed by theexternal pulse oximeter 260 (FIG. 3) as equivalent to the oxygensaturation measured by the internal pulse oximeter 310 (FIG. 3).

[0050] As described above, one particularly advantageous aspect of theUPO is that the operating wavelengths of the sensor 110 (FIG. 3) are notrelevant to the operating wavelengths required by the external pulseoximeter 260 (FIG. 3), i.e. the operating wavelengths that correspond tothe calibration curve or curves utilized by the external pulse oximeter.The calibration curve LUT 440 simply permits generation of a synthesizedwaveform as expected by the external oximeter 260 (FIG. 3) based on thecalibration curve used by the external pulse oximeter 260 (FIG. 3). Thecalibration curve LUT 440 contains data about the known calibrationcurve of the external pulse oximeter 260 (FIG. 3), as specified by themonitor ID input 328. In other words, the waveform actually synthesizedis not a patient plethysmographic waveform. It is merely a storedwaveform that will cause the external pulse oximeter to calculate theproper oxygen saturation valve and pulse rate values. Although this doesnot provide a patient plethysmograph on the external pulse oximeter forthe clinician, the calculated values, which is what is actually sought,will be accurate.

[0051] A modulator 450 responds to an LED drive input 322 to generate amodulated waveform output 324 derived from the first waveform 432 andsecond waveform 434. Also, a data communication interface 460 transmitsas a digital data output 326 the data obtained from the sat 442, pulserate 462 and synthesized waveform 428 inputs.

[0052]FIG. 5 depicts a handheld UPO 500 embodiment. The handheld UPO 500has keypad inputs 510, an LCD display 520, an external power supplyinput 530, an output port 540 for connection to an external pulseoximeter and a sensor input 550 at the top edge (not visible). Thedisplay 520 shows the measured oxygen saturation 522, the measured pulserate 524, a pulsating bar 526 synchronized with pulse rate or pulseevents, and a confidence bar 528 indicating confidence in the measuredvalues of saturation and pulse rate. Also shown are low battery 572 andalarm enabled 574 status indicators.

[0053] The handheld embodiment described in connection with FIG. 5 mayalso advantageously function in conjunction with a docking station thatmechanically accepts, and electrically connects to, the handheld unit.The docking station may be co-located with a patient monitoring systemand connected to a corresponding SpO₂ module sensor port, external powersupply, printer and telemetry device, to name a few options. In thisconfiguration, the handheld UPO may be removed from a first dockingstation at one location to accompany and continuously monitor a patientduring transport to a second location. The handheld UPO can then beconveniently placed into a second docking station upon arrival at thesecond location, where the UPO measurements are displayed on the patientmonitoring system at that location.

[0054]FIG. 6 shows a block diagram of a UPO embodiment, where thefunctions of the UPO 210 are split between a portable pulse oximeter 610and a docking station 660. The portable pulse oximeter 610 (“portable”)is a battery operated, fully functional, standalone pulse oximeterinstrument. The portable 610 connects to a sensor 110 (FIG. 2) through aUPO patient cable 220 (FIG. 2) attached to a patient cable connector618. The portable 610 provides the sensor 110 with a drive signal 612that alternately activates the sensor's red and IR LEDs, as iswell-known in the art. The portable also receives a correspondingdetector signal 614 from the sensor. The portable can also input asensor ID on the drive signal line 612, as described in U.S. Pat. No.5,758,644 entitled Manual and Automatic Probe Calibration, assigned tothe assignee of the present invention and incorporated herein byreference.

[0055] The portable 610 can be installed into the docking station 660 toexpand its functionality. When installed, the portable 610 can receivepower 662 from the docking station 660 if the docking station 660 isconnected to external power 668. Alternately, with no external power 668to the docking station 660, the portable 610 can supply power 662 to thedocking station 660. The portable 610 communicates to the dockingstation with a bi-directional serial data line 664. In particular, theportable 610 provides the docking station with SpO₂, pulse rate andrelated parameters computed from the sensor detector signal 614. Whenthe portable 610 is installed, the docking station 660 may drive a hostinstrument 260 (FIG. 2) external to the portable 610. Alternatively, theportable 610 and docking station 660 combination may function as astandalone pulse oximeter instrument, as described below with respect toFIG. 13.

[0056] In one embodiment, the docking station 660 does not perform anyaction when the portable 610 is not docked. The user interface for thedocking station 660, i.e. keypad and display, is on the portable 610. Anindicator LED on the docking station 660 is lit when the portable isdocked. The docking station 660 generates a detector signal output 674to the host instrument 260 (FIG. 2) in response to LED drive signals 672from the host instrument and SpO₂ values and related parameters receivedfrom the portable 610. The docking station 660 also provides a serialdata output 682, a nurse call 684 and an analog output 688.

[0057] An interface cable 690 connects the docking station 660 to thehost instrument patient cable 230 (FIG. 2). The LED drive signals 672and detector signal output 674 are communicated between the dockingstation 660 and the host instrument 260 (FIG. 2) via the interface cable690. The interface cable 690 provides a sync data output 692 to thedocking station 660, communicating sensor, host instrument (e.g. monitorID 328, FIG. 3) and calibration curve data. Advantageously, this dataallows the docking station 660 to appear to a particular host instrumentas a particular sensor providing patient measurements.

[0058]FIG. 7 provides further detail of the portable 610. The portablecomponents include a pulse oximeter processor 710, a managementprocessor 720, a power supply 730, a display 740 and a keypad 750. Thepulse oximeter processor 710 functions as an internal pulse oximeter,interfacing the portable to a sensor 110 (FIG. 2) and deriving SpO₂,pulse rate, a plethysmograph and a pulse indicator. An advanced pulseoximeter for use as the pulse oximeter processor 710 is described inU.S. Pat. No. 5,632,272, referenced above. An advanced pulse oximetrysensor for use as the sensor 110 (FIG. 2) attached to the pulse oximeterprocessor 710 is described in U.S. Pat. No. 5,638,818, also referencedabove. Further, a line of advanced Masimo SET® pulse oximeter OEM boardsand sensors are available from the assignee of the present invention. Inone embodiment, the pulse oximeter processor 710 is the Masimo SET®MS-3L board or a low power MS-5 board.

[0059] The management processor 720 controls the various functions ofthe portable 610, including asynchronous serial data communications 724with the pulse oximeter processor 710 and synchronous serialcommunications 762 with the docking station 660 (FIG. 6). The physicaland electrical connection to the docking station 660 (FIG. 6) is via adocking station connector 763 and the docking station interface 760,respectively. The processor 720 utilizes a real-time clock 702 to keepthe current date and time, which includes time and date information thatis stored along with SpO₂ parameters to create trend data. The processorof the portable 610 and the docking station 660 (FIG. 6) can be from thesame family to share common routines and minimize code development time.

[0060] The processor 720 also controls the user interface 800 (FIG. 8A)by transferring data 742 to the display 740, including display updatesand visual alarms, and by interpreting keystroke data 752 from thekeypad 750. The processor 720 generates various alarm signals, whenrequired, via an enable signal 728, which controls a speaker driver 770.The speaker driver 770 actuates a speaker 772, which provides audibleindications such as, for example, alarms and pulse beeps. The processor720 also monitors system status, which includes battery status 736,indicating battery levels, and docked status 764, indicating whether theportable 610 is connected to the docking station 660 (FIG. 6). When theportable 610 is docked and is on, the processor 720 also decides when toturn on or off docking station power 732.

[0061] Advantageously, the caregiver can set (i.e. configure or program)the behavior of the portable display 740 and alarms when the dockedportable 610 senses that an interface cable 690 has connected thedocking station 660 to an external pulse oximeter, such as amultiparameter patient monitoring system. In one user setting, forexample, the portable display 740 stops showing the SpO₂ 811 (FIG. 8)and pulse rate 813 (FIG. 8) values when connected to an external pulseoximeter to avoid confusing the caregiver, who can read equivalentvalues on the patient monitoring system. The display 740, however,continues to show the plethysmograph 815 (FIG. 8) and visual pulseindicator 817 (FIG. 8) waveforms. For one such user setting, theportable alarms remain active.

[0062] Another task of the processor 720 includes maintenance of awatchdog function. The watchdog 780 monitors processor status on thewatchdog data input 782 and asserts the :P reset output 784 if a faultis detected. This resets the management processor 720, and the fault isindicated with audible and visual alarms.

[0063] The portable 610 gets its power from batteries in the powersupply 730 or from power 766 supplied from the docking station 660 (FIG.6) via the docking station interface 760. A power manager 790 monitorsthe on/off switch on the keypad 750 and turns-on the portable poweraccordingly. The power manager 790 turns off the portable on command bythe processor 720. DC/DC converters within the power supply 730 generatethe required voltages 738 for operation of the portable 610 and dockingstation power 732. The portable batteries can be either alkalinerechargeable batteries or another renewable power source. The batteriesof the power supply 730 supply docking station power 732 when thedocking station 660 (FIG. 6) is without external power. A batterycharger within the docking station power supply provides chargingcurrent 768 to rechargeable batteries within the power supply 730. Thedocking station power supply 990 (FIG. 9) monitors temperature 734 froma thermistor in the rechargeable battery pack, providing an indicationof battery charge status.

[0064] A non-volatile memory 706 is connected to the managementprocessor 720 via a high-speed bus 722. In the present embodiment, thememory 706 is an erasable and field re-programmable device used to storeboot data, manufacturing serial numbers, diagnostic failure history,adult SpO₂ and pulse rate alarm limits, neonate SpO₂ and pulse ratealarm limits, SpO₂ and pulse rate trend data, and program data. Othertypes of non-volatile memory are well known. The SpO₂ and pulse ratealarm limits, as well as SpO₂ related algorithm parameters, may beautomatically selected based on the type of sensor 110 (FIG. 2), adultor neonate, connected to the portable 610.

[0065] The LCD display 740 employs LEDs for a backlight to increase itscontrast ratio and viewing distance when in a dark environment. Theintensity of the backlight is determined by the power source for theportable 610. When the portable 610 is powered by either a battery packwithin its power supply 730 or a battery pack in the docking stationpower supply 990 (FIG. 9), the backlight intensity is at a minimumlevel. When the portable 610 is powered by external power 668 (FIG. 6),the backlight is at a higher intensity to increase viewing distance andangle. In one embodiment, button on the portable permits overridingthese intensity settings, and provides adjustment of the intensity. Thebacklight is controlled in two ways. Whenever any key is pressed, thebacklight is illuminated for a fixed number of seconds and then turnsoff, except when the portable is docked and derives power from anexternal source. In that case, the backlight is normally on unlessdeactivated with a key on the portable 610.

[0066]FIG. 8A illustrates the portable user interface 800, whichincludes a display 740 and a keypad 750. In one embodiment, the display740 is a dot matrix LCD device having 160 pixels by 480 pixels. Thedisplay 740 can be shown in portrait mode, illustrated in FIG. 8B, or inlandscape mode, illustrated in FIG. 8C. A tilt sensor 950 (FIG. 9) inthe docking station 660 (FIG. 6) or a display mode key on the portable610 (FIG. 6) determines portrait or landscape mode. The tilt sensor 950(FIG. 9) can be a gravity-activated switch or other device responsive toorientation and can be alternatively located in the portable 610 (FIG.6). In a particular embodiment, the tilt sensor 950 (FIG. 9) is anon-mercury tilt switch, part number CW 1300-1, available from ComusInternational, Nutley, N.J. (www.comus-intl.com). The tilt sensor 950(FIG. 9) could also be a mercury tilt switch.

[0067] Examples of how the display area can be used to display SpO₂ 811,pulse rate 813, a plethysmographic waveform 815, a visual pulseindicator 817 and soft key icons 820 in portrait and landscape mode areshown in FIGS. 8B and 8C, respectively. The software program of themanagement processor 720 (FIG. 7) can be easily changed to modify thecategory, layout and size of the display information shown in FIGS.8B-C. Other advantageous information for display is SpO₂ limits, alarm,alarm disabled, exception messages and battery status.

[0068] The keypad 750 includes soft keys 870 and fixed keys 880. Thefixed keys 880 each have a fixed function. The soft keys 870 each have afunction that is programmable and indicated by one of the soft key icons820 located next to the soft keys 870. That is, a particular one of thesoft key icons 820 is in proximity to a particular one of the soft keys870 and has a text or a shape that suggests the function of thatparticular one of the soft keys 870. In one embodiment, the buttonportion of each key of the keypad 750 is constructed of florescentmaterial so that the keys 870, 880 are readily visible in the dark.

[0069] In one embodiment, the keypad 750 has one row of four soft keys870 and one row of three fixed keys 880. Other configurations are, ofcourse, available, and specific arrangement is not significant. Thefunctions of the three fixed keys 880 are power, alarm silence andlight/contrast. The power function is an on/off toggle button. The alarmsilence function and the light/contrast function have dual purposesdepending on the duration of the key press. A momentary press of the keycorresponding to the alarm silence function will disable the audiblealarm for a fixed period of time. To disable the audible alarmindefinitely, the key corresponding to the alarm silence function isheld down for a specified length of time. If the key corresponding tothe alarm silence function is pressed while the audible alarm has beensilenced, the audible alarm is reactivated. If the key corresponding tothe light/contrast function is pressed momentarily, it is an on/offtoggle button for the backlight. If the key corresponding to thelight/contrast function is held down, the display contrast cyclesthrough its possible values.

[0070] In this embodiment, the default functions of the four soft keys870 are pulse beep up volume, pulse beep down volume, menu select, anddisplay mode. These functions are indicated on the display by the uparrow, down arrow, “menu” and curved arrow soft key icons 820,respectively. The up volume and down volume functions increase ordecrease the audible sound or “beep” associated with each detectedpulse. The display mode function rotates the display 740 through allfour orthogonal orientations, including portrait mode (FIG. 8B) andlandscape mode (FIG. 8C), with each press of the corresponding key. Themenu select function allows the functionality of the soft keys 870 tochange from the default functions described above. Examples ofadditional soft key functions that can be selected using this menufeature are set SpO₂ high/low limit, set pulse rate high/low limit, setalarm volume levels, set display to show trend data, print trend data,erase trend data, set averaging time, set sensitivity mode, performsynchronization, perform rechargeable battery maintenance (deepdischarge/recharge to remove battery memory), and display productversion number.

[0071]FIG. 9 provides further details of the docking station 660, whichincludes a docking station processor 910, a non-volatile memory 920, awaveform generator 930, a PROM interface 940, a tilt sensor 950, aportable interface 970 and associated connector 972, status indicators982, a serial data port 682, a nurse call output 684, an analog output688 and a power supply 990. In one embodiment, the docking station 660is intended to be associated with a fixed (non-transportable) hostinstrument, such as a multiparameter patient monitoring instrument in ahospital emergency room. In a transportable embodiment, the dockingstation 660 is movable, and includes a battery pack within the powersupply 990.

[0072] The docking station processor 910 orchestrates the activity onthe docking station 660. The processor 910 provides the waveformgenerator 930 with parameters 932 as discussed above for FIGS. 3 and 4.The processor 910 also provides asynchronous serial data 912 forcommunications with external devices and synchronous serial data 971 forcommunications with the portable 610 (FIG. 6). In addition, theprocessor 910 determines system status including sync status 942, tiltstatus 952 and power status 992. The portable management processor 720(FIG. 7) performs the watchdog function for the docking stationprocessor 910. The docking station processor 910 sends watchdog messagesto the portable processor 720 (FIG. 7) as part of the synchronous serialdata 972 to ensure the correct operation of the docking stationprocessor 910.

[0073] The docking station processor 910 accesses non-volatile memory920 over a high-speed bus 922. The non-volatile memory 920 isre-programmable and contains program data for the processor 910including instrument communication protocols, synchronizationinformation, a boot image, manufacturing history and diagnostic failurehistory.

[0074] The waveform generator 930 generates a synthesized waveform thata conventional pulse oximeter can process to calculate SpO₂ and pulserate values or exception messages, as described above with respect toFIG. 4. However, in the present embodiment, as explained above, thewaveform generator output does not reflect a physiological waveform. Itis merely a waveform constructed to cause the external pulse oximeter tocalculate the correct saturation and pulse rate. In an alternativeembodiment, physiological data could be provided to the external pulseoximeter, but the external pulse oximeter would generally not be able tocalculate the proper saturation values, and the upgrading feature wouldbe lost. The waveform generator 930 is enabled if an interface cable 690(FIG. 6), described below with respect to FIG. 10, with validsynchronization information is connected. Otherwise, the power to thewaveform generator 930 is disabled.

[0075] The status indicators 982 are a set of LEDs on the front of thedocking station 660 used to indicate various conditions includingexternal power (AC), portable docked, portable battery charging, dockingstation battery charging and alarm. The serial data port 682 is used tointerface with either a computer, a serial port of conventional pulseoximeters or serial printers via a standard RS-232 DB-9 connector 962.This port 682 can output trend memory, SpO₂ and pulse rate and supportthe system protocols of various manufacturers. The analog output 688 isused to interface with analog input chart recorders via a connector 964and can output “real-time” or trend SpO₂ and pulse rate data. The nursecall output 684 from a connector 964 is activated when alarm limits areexceeded for a predetermined number of consecutive seconds. In anotherembodiment, data, including alarms, could be routed to any number ofcommunications ports, and even over the Internet, to permit remote useof the upgrading pulse oximeter.

[0076] The PROM interface 940 accesses synchronization data 692 from thePROM 1010 (FIG. 10) in the interface cable 690 (FIGS. 6, 10) andprovides synchronization status 942 to the docking station processor910. The portable interface 970 provides the interconnection to theportable 610 (FIG. 6) through the docking station interface 760 (FIG.7).

[0077] As shown in FIG. 9, external power 668 is provided to the dockingstation 660 through a standard AC connector 968 and on/off switch 969.When the docking station 660 has external power 668, the power supply990 charges the battery in the portable power supply 730 (FIG. 7) andthe battery, if any, in the docking station power supply 990. When theportable 610 (FIG. 6) is either removed or turned off, the dockingstation power 973 is removed and the docking station 660 is turned off,except for the battery charger portion of the power supply 990. Thedocking station power 973 and, hence, the docking station 660 turn onwhenever a docked portable 610 (FIG. 6) is turned on. The portable 610(FIG. 6) supplies power for an embodiment of the docking station 660without a battery when external power 668 is removed or fails.

[0078]FIG. 10 provides further detail regarding the interface cable 690used to connect between the docking station 660 (FIG. 6) and the patientcable 230 (FIG. 2) of a host instrument 260 (FIG. 2). The interfacecable 690 is configured to interface to a specific host instrument andto appear to the host instrument as a specific sensor. A PROM 1010 builtinto the interface cable 690 contains information identifying a sensortype, a specific host instrument, and the calibration curve of thespecific host instrument. The PROM information can be read by thedocking station 660 (FIG. 6) as synchronization data 692.Advantageously, the synchronization data 692 allows the docking station660 (FIG. 6) to generate a waveform to the host instrument that causesthe host instrument to display SpO₂ values equivalent to thosecalculated by the portable 610 (FIG. 6). The interface cable 690includes an LED drive path 672. In the embodiment shown in FIG. 10, theLED drive path 672 is configured for common anode LEDs and includes IRcathode, red cathode and common anode signals. The interface cable 690also includes a detector drive path 674, including detector anode anddetector cathode signals.

[0079] A menu option on the portable 610 (FIG. 6) also allowssynchronization information to be calculated in the field. With manualsynchronization, the docking station 660 (FIG. 6) generates a waveformto the host instrument 260 (FIG. 2) and displays an expected SpO₂ value.The user enters the SpO₂ value displayed on the host instrument usingthe portable keypad 750 (FIG. 7). These steps are repeated until apredetermined number of data points are entered and the SpO₂ valuesdisplayed by the portable and the host instrument are consistent.

[0080] FIGS. 11A-B depict an embodiment of the portable 610, asdescribed above with respect to FIG. 6. FIGS. 12A-B depict an embodimentof the docking station 660, as described above with respect to FIG. 6.FIG. 13 depicts an embodiment of the UPO 210 where the portable 610 isdocked with the docking station 660, also as described above withrespect to FIG. 6.

[0081]FIG. 11A depicts the portable front panel 1110. The portable 610has a patient cable connector 618, as described above with respect toFIG. 6. Advantageously, the connector 618 is rotatably mounted so as tominimize stress on an attached patient cable (not shown). In oneembodiment, the connector 618 can freely swivel between a plane parallelto the front panel 1110 and a plane parallel to the side panel 1130. Inanother embodiment, the connector 618 can swivel between, and bereleasably retained in, three locked positions. A first locked positionis as shown, where the connector is in a plane parallel to the frontpanel 1110. A second locked position is where the connector 618 is in aplane parallel to the side panel 1130. The connector 618 also has anintermediate locked position 45° between the first and the second lockedpositions. The connector 618 is placed in the first locked position forattachment to the docking station 660.

[0082] Shown in FIG. 11A, the portable front panel 1110 also has aspeaker 772, as described with respect to FIG. 7. Further, the frontpanel 1110 has a row of soft keys 870 and fixed keys 880, as describedabove with respect to FIG. 8. In addition, the front panel 1110 has afinger actuated latch 1120 that locks onto a corresponding catch 1244(FIG. 12A) in the docking station 660, allowing the portable 610 to bereleasably retained by the docking station 660. An OEM label can beaffixed to a recessed area 1112 on the front panel 1110.

[0083]FIG. 11B depicts the portable back panel 1140. The back panel 1140has a socket 763, a pole clamp mating surface 1160, and a battery packcompartment 1170. The socket 763 is configured to mate with acorresponding docking station plug 972 (FIG. 12A). The socket 763 andplug 972 (FIG. 12A) provide the electrical connection interface betweenthe portable 610 and the docking station 660 (FIG. 12A). The socket 763houses multiple spring contacts that compress against platededge-connector portions of the docking station plug 972 (FIG. 12A). Aconventional pole clamp (not shown) may be removably attached to themating surface 1160. This conveniently allows the portable 610 to beheld to various patient-side or bedside mounts for hands-free pulseoximetry monitoring. The portable power supply 730 (FIG. 7) is containedwithin the battery pack compartment 1170. The compartment 1170 has aremovable cover 1172 for protection, insertion and removal of theportable battery pack. Product labels, such as a serial numberidentifying a particular portable, can be affixed with the back panelindent 1142.

[0084]FIG. 12A depicts the front side 1210 of the docking station 660.The front side 1210 has a docking compartment 1220, a pole clamp recess1230, pivots 1242, a catch 1244, a plug connector 972 and LED statusindicators 982. The docking compartment 1220 accepts and retains theportable 610 (FIGS. 11A-B), as shown in FIG. 13. When the portable 610(FIGS. 11A-B) is docked in the compartment 1220, the pole clamp recess1230 accommodates a pole clamp (not shown) attached to the portable'spole clamp mating surface 1160 (FIG. 11B), assuming the pole clamp is inits closed position. The portable 610 (FIGS. 11A-B) is retained in thecompartment 1220 by pivots 1242 that fit into corresponding holes in theportable's side face 1130 and a catch 1244 that engages the portable'slatch 1120 (FIG. 11A). Thus, the portable 610 (FIGS. 11A-B) is docked byfirst attaching it at one end to the pivots 1242, then rotating it aboutthe pivots 1242 into the compartment 1220, where it is latched in placeon the catch 1244. The portable 610 (FIGS. 11A-B) is undocked in reverseorder, by first pressing the latch 1120 (FIG. 11A), which releases theportable from the catch 1244, rotating the portable 610 (FIGS. 11A-B)about the pivots 1242 out of the compartment 1220 and then removing itfrom the pivots 1242. As the portable is rotated into the compartment,the docking station plug 972 inserts into the portable socket 763 (FIG.11B), providing the electrical interface between the portable 610 andthe docking station 660. The status indicators 982 are as describedabove with respect to FIG. 9.

[0085]FIG. 12B depicts the back side 1260 of the docking station 660.The back side 1260 has a serial (RS-232 or USB) connector 962, an analogoutput and nurse call connector 964, an upgrade port connector 966, anAC power plug 968, an on/off switch 969 and a ground lug 1162. A handle1180 is provided at one end and fan vents 1170 are provided at theopposite end. A pair of feet 1190 are visible near the back side 1260. Acorresponding pair of feet (not visible) are located near the front side1210 (FIG. 12A). The feet near the front side 1210 extend so as to tiltthe front side 1210 (FIG. 12A) upward, making the display 740 (FIG. 13)of a docked portable 610 (FIG. 13) easier to read.

[0086]FIG. 13 illustrates both the portable 610 and the docking station660. The portable 610 and docking station 660 constitute three distinctpulse oximetry instruments. First, the portable 610 by itself, asdepicted in FIGS. 11A-B, is a handheld pulse oximeter applicable tovarious patient monitoring tasks requiring battery power or significantmobility, such as ambulance and ER situations. Second, the portable 610docked in the docking station 660, as depicted in FIG. 13, is astandalone pulse oximeter applicable to a wide-range of typical patientmonitoring situations from hospital room to the operating room. Third,the portable 610 docked and the upgrade port 966 (FIG. 12B) connectedwith an interface cable to the sensor port of a conventional pulseoximeter module 268 (FIG. 2) within a multiparameter patient monitoringinstrument 260 (FIG. 2) or other conventional pulse oximeter, is auniversal/upgrading pulse oximeter (UPO) instrument 210, as describedherein. Thus, the portable 610 and docking station 660 configuration ofthe UPO 210 advantageously provides a three-in-one pulse oximetryinstrument functionality.

[0087] Another embodiment of the docking station 660 incorporates aninput port that connects to a blood pressure sensor and an output portthat connects to the blood pressure sensor port of a multiparameterpatient monitoring system (MPMS). The docking station 660 incorporates asignal processor that computes a blood pressure measurement based uponan input from the blood pressure sensor. The docking station 660 alsoincorporates a waveform generator connected to the output port thatproduces a synthesized waveform based upon the computed measurement. Thewaveform generator output is adjustable so that the blood pressure valuedisplayed on the MPMS is equivalent to the computed blood pressuremeasurement. Further, when the portable 610 is docked in the dockingstation 660 and the blood pressure sensor is connected to the inputport, the portable displays a blood pressure value according to thecomputed blood pressure measurement. Thus, in this embodiment, thedocking station 660 provides universal/upgrading capability for bothblood pressure and SpO₂.

[0088] Likewise, the docking station 660 can function as anuniversal/upgrading instrument for other vital sign measurements, suchas respiratory rate, EKG or EEG. For this embodiment, the dockingstation 660 incorporates related sensor connectors and associated sensorsignal processors and upgrade connectors to an MPMS or standaloneinstrument. In this manner, a variety of vital sign measurements can beincorporated into the docking station 660, either individually or incombination, with or without SpO₂ as a measurement parameter, and withor without the portable 610. In yet another embodiment, the dockingstation 660 can be configured as a simple SpO₂ upgrade box,incorporating a SpO₂ processor and patient cable connector for a SpO₂sensor that functions with or without the portable 610.

[0089] Unlike a conventional standalone pulse oximeter, the standaloneconfiguration shown in FIG. 13 has a rotatable display 740 that allowsthe instrument to be operated in either a vertical or horizontalorientation. A tilt sensor 950 (FIG. 9) indicates when the bottom face1310 is placed along a horizontal surface or is otherwisehorizontally-oriented. In this horizontal orientation, the display 740appears in landscape mode (FIG. 8C). The tilt sensor 950 (FIG. 9) alsoindicates when the side face 1320 is placed along a horizontal surfaceor is otherwise horizontally oriented. In this vertical orientation, thedisplay 740 appears in portrait mode (FIG. 8B). A soft key 870 on theportable 610 can override the tilt sensor, allowing the display to bepresented at any 90° orientation, i.e. portrait, landscape,“upside-down” portrait or “upside-down” landscape orientations. Thehandheld configuration (FIG. 11A), can also present the display 740 atany 90° orientation using a soft key 870. In the particular embodimentdescribed above, however, the portable 610 does not have a tilt sensorand, hence, relies on a soft key 870 to change the orientation of thedisplay when not docked.

[0090]FIG. 14 illustrates the docking station 660 incorporated within alocal area network (LAN). The LAN shown is Ethernet-based 1460, using acentral LAN server 1420 to interconnect various LAN clients 1430 andother system resources such as printers and storage (not shown). AnEthernet controller module 1410 is incorporated with the docking station660. The controller module 1410 can be incorporated within the dockingstation 660 housing or constructed as an external unit. In this manner,the UPO, according to the present invention, can communicate with otherdevices on the LAN or over the Internet 1490.

[0091] The Ethernet controller module 1410 can be embedded with webserver firmware, such as the Hewlett-Packard (HP) BFOOT-10501. Themodule 1410 has both a 10 Base-T Ethernet interface for connection tothe Ethernet 1460 and a serial interface, such as RS-232 or USB, forconnection to the docking station 660. The module firmware incorporatesHTTP and TCP/IP protocols for standard communications over the WorldWide Web. The firmware also incorporates a micro web server that allowscustom web pages to be served to remote clients over the Internet, forexample. Custom C++ programming allows expanded capabilities such asdata reduction, event detection and dynamic web page configuration.

[0092] As shown in FIG. 14, there are many applications for the dockingstation 660 to Ethernet interface. Multiple UPOs can be connected to ahospital's LAN, and a computer on the LAN could be utilized to uploadpulse rate and saturation data from the various UPOs, displaying theresults. Thus, this Ethernet interface could be used to implement acentral pulse oximetry monitoring station within a hospital. Further,multiple UPOs from anywhere in the world can be monitored from a centrallocation via the Internet. Each UPO is addressable as an individual website and downloads web pages viewable on a standard browser, the webpages displaying oxygen saturation, pulse rate and related physiologicalmeasurements from the UPO. This feature allows a caregiver to monitor apatient regardless of where the patient or caregiver is located. Forexample a caregiver located at home in one city or at a particularhospital could download measurements from a patient located at home in adifferent city or at the same or a different hospital. Otherapplications include troubleshooting newly installed UPOs or uploadingsoftware patches or upgrades to UPOs via the Internet. In additionalarms could be forwarded to the URL of the clinician monitoring thepatient.

[0093] The UPO may have other configurations besides the handheld unitdescribed in connection with FIG. 5 or the portable 610 and dockingstation 660 combination described in connection with FIGS. 11-13. TheUPO may be a module, with or without a display, that can be removablyfastened to a patient via an arm strap, necklace or similar means. In asmaller embodiment, this UPO module may be integrated into a cable orconnector used for attaching a sensor to a pulse oximeter. The UPO mayalso be a circuit card or module that can externally or internally pluginto or mate with a standalone pulse oximeter or multiparameter patientmonitoring system. Alternatively, the UPO may be configured as a simplestandalone upgrade instrument.

[0094] Further, although a universal/upgrading apparatus and method havebeen mainly described in terms of a pulse oximetry measurementembodiment, the present invention is equally applicable to otherphysiological measurement parameters such as blood pressure, respirationrate, EEG and ECG, to name a few. In addition, a universal/upgradinginstrument having a single physiological measurement parameter or amultiple measurement parameter capability and configured as a handheld,standalone, portable, docking station, module, plug-in, circuit card, toname a few, is also within the scope of the present invention.

[0095] The UPO has been disclosed in detail in connection with variousembodiments of the present invention. These embodiments are disclosed byway of examples only and are not to limit the scope of the presentinvention, which is defined by the claims that follow. One of ordinaryskill in the art will appreciate many variations and modificationswithin the scope of this invention.

What is claimed is:
 1. A pulse oximeter attachment comprising: a firstpath adapted to communicate an LED drive current from a host instrument;a second path adapted to communicate a waveform responsive to said LEDdrive current to said host instrument; a memory device; and calibrationdata corresponding to said waveform stored in said memory device, saidcalibration data readable from said memory device so as to enable saidhost instrument to calculate an accurate oxygen saturation value.
 2. Thepulse oximeter attachment according to claim 1, wherein said first pathand said second path are configured to mechanically and electricallyattach to a sensor port of said host instrument.
 3. The pulse oximeterattachment according to claim 1, wherein said calibration data relates aratio derivable from said waveform to said oxygen saturation value.
 4. Amethod of acquiring calibration information, the method comprising:providing an LED drive path; providing an a detector drive path;providing a memory interface; receiving a drive current on said LEDdrive path; transmitting a waveform on said detector drive path inresponse to said drive current; uploading stored calibration informationover said interface; and utilizing said calibration information torelate said waveform to oxygen saturation.
 5. The method according toclaim 4, wherein said utilizing comprises relating ratios correspondingto said waveform to said oxygen saturation.
 6. A pulse oximeterattachment comprising: a first path adapted to communicate a sensordrive signal from a host instrument; a second path adapted tocommunicate information responsive to said sensor drive signal to saidhost instrument; a memory device; and calibration data stored in saidmemory device and adapted to be read from said memory device tocalculate an oxygen saturation value.
 7. The pulse oximeter attachmentaccording to claim 6, wherein the information comprises a waveform. 8.The pulse oximeter attachment according to claim 6, wherein saidcalibration data relates a ratio derivable from said information to saidoxygen saturation value.
 9. A pulse oximeter comprising: a port; a firstpath adapted to communicate an LED drive current to an attachmentcommunicating with said port; a second path adapted to communicate awaveform responsive to said LED drive current from said port; aninterface adapted to read calibration data from said attachment; and aprocessor configured to correspond oxygen saturation with saidcalibration data and said waveform.
 10. The pulse oximeter according toclaim 9, wherein said port comprises a sensor port.
 11. The pulseoximeter according to claim 9, wherein said port comprises a data port.12. The pulse oximeter according to claim 9, wherein said calibrationdata relates a ratio derivable from said waveform to said oxygensaturation.
 13. A method of uploading calibration data associated with apulse oximetry sensor, the method comprising: communicating an LED drivecurrent configured to drive a pulse oximetry sensor; receiving awaveform responsive to said LED drive current; and uploading calibrationdata associated with the pulse oximetry sensor.
 14. The method accordingto claim 13, further comprising calculating an oxygen saturation fromsaid waveform.
 15. The method according to claim 13, further comprisingcalculating an oxygen saturation from said waveform and said calibrationdata.
 16. A pulse oximeter comprising: an LED drive signal adapted to betransmitted to a sensor; a detector signal adapted to received from thesensor in response to said LED drive signal; an interface configured toaccess calibration data from an attached memory; a processor responsiveto said detector signal and said calibration data; and an oxygensaturation display responsive to said processor.
 17. A methodcomprising: transmitting an LED drive current to a removable attachment;receiving a detector signal in response to said LED drive current;uploading calibration data from the removable attachment; and utilizingsaid calibration data to display an oxygen saturation consistent withsaid detector signal.
 18. An apparatus for storing calibration data usedby a processor calculating parameters associated with pulsing blood, theapparatus comprising: means for outputting light to be transmittedthrough body tissue carrying pulsing blood; means for outputting anintensity signal responsive to the light; and means for storing thecalibration data remote to an oximeter including a processor configuredto calculate oxygen saturation of pulsing blood.
 19. The apparatus ofclaim 18, wherein the calibration data is associated with at least oneof the means for outputting.